Switching supplies

[Chad Clendening]

I have never traced it out,  basically they use a 555 timer with a few transistors to switch power through a transformer.  Then it
gets rectified and regulated to roughly 8 volts.

The processor uses a 7805 type regulator to get 5 volts out.  3 volts drop means minimal power dissipation.  At the same time, at
least 8 volts is present with as low as 5 volts from the battery.

National has many examples with their Simple Switcher  series.  I believe Motorola, Micrel  and a few others have equivalents also.
The actual number was something like LM2575 ( don't quote me as I havn't looked at these for a few months).


Chad


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> ------------------------------
>
> Date: Mon, 16 Oct 2000 22:19:07 -0500
> From: Tom Sharpe <twsharpe at mtco.com>
> Subject: Re: Heatsinking, Chryslers
>
> How about an example circuit?
>
> Jeff Webb wrote:
>
> > Chad Clendening wrote:
> > >
> > > In addition to using the inlet air to cool the power drivers, the Chrysler's use  a switching pre-regulator to make a 7.5 to 8
> > > volt power supply.  This setup not only allows the linear 5 volt regulator to  operate with minimal power dissipation, it also
> > > allows the ECM to operate with 4 to 5 volts at the battery, probably well below the limitations of other EFI components.
> >
> > Since Nic brought up the switching regulator topic, I've been thinking
> > about doing something like this.  Seems like a pretty good idea.
> >
> > Jeff Webb


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